Problem: Solve for $z$ : $10 = z + 8$
Subtract $8$ from both sides: $ \begin{eqnarray} \\ \hphantom{10 {- 8}} &\hphantom{=}& \hphantom{z} \\ 10 &=& z + 8 \\ \\ {-8} && {-8} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 10 {- 8} &=& z \\ \end{eqnarray} $ Simplify. $ z = 2$